You kick your feet gently to stay above the water and filled your lungs with as much of the air as they could hold. The particular lightness or even a nothingness of the air was a surprise. Your chest didn't strain to hold the deep breath. Your mouth wasn't cooled by the air as it rushed by. It was almost nonexistent. And yet there was no struggle for oxygen; your mind and body remained clear and focused.
You allow yourself to forget the strangness of your environment for a moment and calmly call into the darkness, "Hello." You expect your voice to echo against the cold, steel barriers of the tank, but there was nothing.